With rapid development of packet services and intelligent terminals, high-speed large-data-volume services have a growing demand for spectrums. A low frequency band is usually a spectrum in a range of below 3 GHz. A centimetric wave frequency band is usually a spectrum ranging from 3 GHz to 30 GHz. A millimetric wave frequency band is usually a spectrum ranging from 30 GHz to 300 GHz. A frequency band of about 2 GHz or lower is usually used in conventional cellular communications. In the conventional cellular communications, a common signal of a cell, such as system information, is usually sent by means of omni transmission, resulting in relatively large power consumption of a base station.